[Qemu-devel] [PATCH for-2.8 v2 0/2] loader fixes

[Qemu-devel] [PATCH for-2.8 v2 0/2] loader fixes

[Laszlo Ersek]

Version 2 of
<http://lists.nongnu.org/archive/html/qemu-devel/2016-11/msg05012.html>,
with the checkpatch error fixed.

Thanks
Laszlo

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Michael Walle <michael@walle.cc>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Shannon Zhao <zhaoshenglong@huawei.com>
Cc: qemu-arm@nongnu.org
Cc: qemu-devel@nongnu.org

Laszlo Ersek (2):
  loader: fix handling of custom address spaces when adding ROM blobs
  loader: fix undefined behavior in rom_order_compare()

 hw/lm32/lm32_hwsetup.h   | 2 +-
 include/hw/loader.h      | 6 +++---
 hw/arm/virt-acpi-build.c | 2 +-
 hw/core/loader.c         | 6 ++++--
 hw/i386/acpi-build.c     | 2 +-
 5 files changed, 10 insertions(+), 8 deletions(-)

-- 
2.9.2

[Qemu-devel] [PATCH for-2.8 v2 1/2] loader: fix handling of custom address spaces when adding ROM blobs

[Laszlo Ersek]

* Commit 3e76099aacb4 ("loader: Allow a custom AddressSpace when loading
  ROMs") introduced the "Rom.as" field:

  (1) It modified the utility callers of rom_insert() to take "as" as a
      new parameter from *their* callers, and set "rom->as" from that
      parameter. The functions covered were rom_add_file() and
      rom_add_elf_program().

  (2) It also modified rom_insert() itself, to auto-assign
      "&address_space_memory", in case the external caller passed -- and
      the utility caller forwarded -- as=NULL.

  Except, commit 3e76099aacb4 forgot to update the third utility caller of
  rom_insert(), under point (1), namely rom_add_blob().

* Later, commit 5e774eb3bd264 ("loader: Add AddressSpace loading support
  to uImages") added the load_uimage_as() function, and the
  rom_add_blob_fixed_as() function-like macro, with the necessary changes
  elsewhere to propagate the new "as" parameter to rom_add_blob():

    load_uimage_as()
      load_uboot_image()
        rom_add_blob_fixed_as()
          rom_add_blob()

  At this point, the signature (and workings) of rom_add_blob() had been
  broken already, and the rom_add_blob_fixed_as() macro passed its "_as"
  parameter to rom_add_blob() as "callback_opaque". Given that the
  "fw_callback" parameter itself was set to NULL (correctly), this did no
  additional damage (the opaque arg would never be used), but ultimately
  it broke the new functionality of load_uimage_as().

* The load_uimage_as() function would be put to use in one of the later
  patches, commit e481a1f63c93 ("generic-loader: Add a generic loader").

* We can fix this only in a unified patch now. Append "AddressSpace *as"
  to the signature of rom_add_blob(), and handle the new parameter. Pass
  NULL from all current callers, except from rom_add_blob_fixed_as(),
  where "_as" has to be bumped to the proper position.

* Note that rom_add_file() rejects the case when both "mr" and "as" are
  passed in as non-NULL. The action that this is apparently supposed to
  prevent is the

    rom->mr = mr;

  assignment (that's the only place where the "mr" parameter is used in
  rom_add_file()). In rom_add_blob() though, we have no "mr" parameter,
  and the actions done on the fw_cfg branch:

    if (fw_file_name && fw_cfg) {
        if (mc->rom_file_has_mr) {
            data = rom_set_mr(rom, OBJECT(fw_cfg), devpath);
            mr = rom->mr;
        } else {
            data = rom->data;
        }

  reflect those that are performed by rom_add_file() too (with mr==NULL):

    if (rom->fw_file && fw_cfg) {
        if ((!option_rom || mc->option_rom_has_mr) &&
            mc->rom_file_has_mr) {
            data = rom_set_mr(rom, OBJECT(fw_cfg), devpath);
        } else {
            data = rom->data;
        }

  Hence we need no additional restrictions in rom_add_blob().

* Stable is not affected as both problematic commits appeared first in
  v2.8.0-rc0.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Michael Walle <michael@walle.cc>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: Shannon Zhao <zhaoshenglong@huawei.com>
Cc: qemu-arm@nongnu.org
Cc: qemu-devel@nongnu.org
Fixes: 3e76099aacb4dae0d37ebf95305369e03d1491e6
Fixes: 5e774eb3bd264c76484906f4bd0fb38e00b8090e
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
---

Notes:
    v2:
    - no changes, pick up R-b's from Alistair and Michael

 hw/lm32/lm32_hwsetup.h   | 2 +-
 include/hw/loader.h      | 6 +++---
 hw/arm/virt-acpi-build.c | 2 +-
 hw/core/loader.c         | 4 +++-
 hw/i386/acpi-build.c     | 2 +-
 5 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/hw/lm32/lm32_hwsetup.h b/hw/lm32/lm32_hwsetup.h
index b71e6eafba48..23e18784dffd 100644
--- a/hw/lm32/lm32_hwsetup.h
+++ b/hw/lm32/lm32_hwsetup.h
@@ -75,7 +75,7 @@ static inline void hwsetup_create_rom(HWSetup *hw,
         hwaddr base)
 {
     rom_add_blob("hwsetup", hw->data, TARGET_PAGE_SIZE,
-                 TARGET_PAGE_SIZE, base, NULL, NULL, NULL);
+                 TARGET_PAGE_SIZE, base, NULL, NULL, NULL, NULL);
 }
 
 static inline void hwsetup_add_u8(HWSetup *hw, uint8_t u)
diff --git a/include/hw/loader.h b/include/hw/loader.h
index 038170624d8f..0c864cfd6046 100644
--- a/include/hw/loader.h
+++ b/include/hw/loader.h
@@ -180,7 +180,7 @@ MemoryRegion *rom_add_blob(const char *name, const void *blob, size_t len,
                            size_t max_len, hwaddr addr,
                            const char *fw_file_name,
                            FWCfgReadCallback fw_callback,
-                           void *callback_opaque);
+                           void *callback_opaque, AddressSpace *as);
 int rom_add_elf_program(const char *name, void *data, size_t datasize,
                         size_t romsize, hwaddr addr, AddressSpace *as);
 int rom_check_and_register_reset(void);
@@ -194,7 +194,7 @@ void hmp_info_roms(Monitor *mon, const QDict *qdict);
 #define rom_add_file_fixed(_f, _a, _i)          \
     rom_add_file(_f, NULL, _a, _i, false, NULL, NULL)
 #define rom_add_blob_fixed(_f, _b, _l, _a)      \
-    rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, NULL)
+    rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, NULL, NULL)
 #define rom_add_file_mr(_f, _mr, _i)            \
     rom_add_file(_f, NULL, 0, _i, false, _mr, NULL)
 #define rom_add_file_as(_f, _as, _i)            \
@@ -202,7 +202,7 @@ void hmp_info_roms(Monitor *mon, const QDict *qdict);
 #define rom_add_file_fixed_as(_f, _a, _i, _as)          \
     rom_add_file(_f, NULL, _a, _i, false, NULL, _as)
 #define rom_add_blob_fixed_as(_f, _b, _l, _a, _as)      \
-    rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, _as)
+    rom_add_blob(_f, _b, _l, _l, _a, NULL, NULL, NULL, _as)
 
 #define PC_ROM_MIN_VGA     0xc0000
 #define PC_ROM_MIN_OPTION  0xc8000
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index f953610018c4..d4160dfa7d34 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -809,7 +809,7 @@ static MemoryRegion *acpi_add_rom_blob(AcpiBuildState *build_state,
                                        uint64_t max_size)
 {
     return rom_add_blob(name, blob->data, acpi_data_len(blob), max_size, -1,
-                        name, virt_acpi_build_update, build_state);
+                        name, virt_acpi_build_update, build_state, NULL);
 }
 
 static const VMStateDescription vmstate_virt_acpi_build = {
diff --git a/hw/core/loader.c b/hw/core/loader.c
index 6e022b5ad583..c0d645a87134 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -978,7 +978,8 @@ err:
 
 MemoryRegion *rom_add_blob(const char *name, const void *blob, size_t len,
                    size_t max_len, hwaddr addr, const char *fw_file_name,
-                   FWCfgReadCallback fw_callback, void *callback_opaque)
+                   FWCfgReadCallback fw_callback, void *callback_opaque,
+                   AddressSpace *as)
 {
     MachineClass *mc = MACHINE_GET_CLASS(qdev_get_machine());
     Rom *rom;
@@ -986,6 +987,7 @@ MemoryRegion *rom_add_blob(const char *name, const void *blob, size_t len,
 
     rom           = g_malloc0(sizeof(*rom));
     rom->name     = g_strdup(name);
+    rom->as       = as;
     rom->addr     = addr;
     rom->romsize  = max_len ? max_len : len;
     rom->datasize = len;
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 45a2ccfc4c60..9708cdc463df 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -2936,7 +2936,7 @@ static MemoryRegion *acpi_add_rom_blob(AcpiBuildState *build_state,
                                        uint64_t max_size)
 {
     return rom_add_blob(name, blob->data, acpi_data_len(blob), max_size, -1,
-                        name, acpi_build_update, build_state);
+                        name, acpi_build_update, build_state, NULL);
 }
 
 static const VMStateDescription vmstate_acpi_build = {
-- 
2.9.2

[Qemu-devel] [PATCH for-2.8 v2 2/2] loader: fix undefined behavior in rom_order_compare()

[Laszlo Ersek]

According to ISO C99 / N1256 (referenced in HACKING):

> 6.5.8 Relational operators
>
> 4 For the purposes of these operators, a pointer to an object that is
>   not an element of an array behaves the same as a pointer to the first
>   element of an array of length one with the type of the object as its
>   element type.
>
> 5 When two pointers are compared, the result depends on the relative
>   locations in the address space of the objects pointed to. If two
>   pointers to object or incomplete types both point to the same object,
>   or both point one past the last element of the same array object, they
>   compare equal. If the objects pointed to are members of the same
>   aggregate object, pointers to structure members declared later compare
>   greater than pointers to members declared earlier in the structure,
>   and pointers to array elements with larger subscript values compare
>   greater than pointers to elements of the same array with lower
>   subscript values. All pointers to members of the same union object
>   compare equal. If the expression /P/ points to an element of an array
>   object and the expression /Q/ points to the last element of the same
>   array object, the pointer expression /Q+1/ compares greater than /P/.
>   In all other cases, the behavior is undefined.

Our AddressSpace objects are allocated generally individually, and kept in
the "address_spaces" linked list, so we mustn't compare their addresses
with relops.

Convert the pointers subjected to the relop in rom_order_compare() to
"uintptr_t":

> 7.18.1.4 Integer types capable of holding object pointers
>
> 1 [...]
>
>   The following type designates an unsigned integer type with the
>   property that any valid pointer to void can be converted to this type,
>   then converted back to pointer to void, and the result will compare
>   equal to the original pointer:
>
>   /uintptr_t/
>
>   These types are optional.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Alistair Francis <alistair.francis@xilinx.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-devel@nongnu.org
Fixes: 3e76099aacb4dae0d37ebf95305369e03d1491e6
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
---

Notes:
    v2:
    - fix checkpatch error (also verify with the script)
    - pick up R-b from Alistair

 hw/core/loader.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index c0d645a87134..45742494e6fd 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -818,7 +818,7 @@ static QTAILQ_HEAD(, Rom) roms = QTAILQ_HEAD_INITIALIZER(roms);
 
 static inline bool rom_order_compare(Rom *rom, Rom *item)
 {
-    return (rom->as > item->as) ||
+    return ((uintptr_t)(void *)rom->as > (uintptr_t)(void *)item->as) ||
            (rom->as == item->as && rom->addr >= item->addr);
 }
 
-- 
2.9.2